The Curious Case of Woodcreepers: Cytogenomic Evidence Based on the Position of NORs

Woodcreepers (Dendrocolaptinae) constitute a subfamily of Neotropical passerines currently recognized as a monophyletic group within Furnariidae. Although Furnariidae is one of the most diverse avian families in the Neotropics, cytogenetic data remain scarce. In this study, we present the first cytogenetic analysis of Lepidocolaptes falcinellus using conventional (Ag-NOR, C-banding) and molecular (hybridization in situ fluorescence—FISH with telomeric and 18S rDNA probes) approaches. The species exhibits a karyotype with 2n = 80 chromosomes, predominantly acrocentric macrochromosomes, and heterochromatin restricted to centromeric regions. Telomeric repeats were confined to terminal regions, and 18S rDNA sites (NORs) were detected on the short arm of chromosome pair 1. This pattern, also observed in other Dendrocolaptinae species, contrasts with the ancestral avian condition of NORs on microchromosomes, suggesting a derived, lineage-specific chromosomal signature. These results support the cytogenetic cohesion of Dendrocolaptinae and reinforce the potential of NOR localization as a phylogenetic marker within the group. Our findings contribute novel cytotaxonomic data that enhance the understanding of chromosomal evolution and systematics in Furnariidae.